Stationary Channel Factors and Signal Disturbances in a Direct Converter Receiver in a System with MIMO Joint Estimation Algorithm

Abstract

The article discusses the algorithm for the joint estimation of the stationary channel factors and signal distortions, such as DC drift, the frequency shift remaining from the demodulation procedure, amplitude and phase imbalance (IQ-imbalance). The problem of estimating unknown parameters is solved in two stages, by combining two procedures. The first, based on the polynomial approximation of the generalized communication channel and the linear least squares (MLS) method, estimates the constant components of the signal quadrature, amplitude and phase imbalance, as well as a rough estimate of the channel frequency and factors. The second procedure is synthesized using the Taylor approximation, a modified method of least squares in the form of a functional A.N. Tikhonov and regularization method. It is a nonlinear recursive algorithm for obtaining a more accurate estimate of the frequency and channel factors. This approach allows a sufficiently high estimation accuracy to reduce the complexity of the algorithm compared to using only the second procedure. The resulting algorithm works under conditions of uncorrelated Rayleigh fading in MIMO systems with spatial multiplexing with a priori uncertainty regarding the statistical characteristics of the communication channel (except for the dispersion of additive noise) and the laws of noise distribution, both phase and additive.